Honestly I don't think Dorry and Brogy are going to be cured this arc, I think they are endgame Zoro and Sanji opponents for the Final War. Oda planned for them to become turned and become Zoro and Sanji's opponents as two of Imu's highest ranking commanders, from the very beginning. That's why they had the hunting competition parallel in Little Garden. They will be cured later on during the final conflict most likely and join Luffy's side again.

I think Imu is going to leave and take Dorry and Brogy with them. I could also see Vivi meeting them in demon forms again after Imu kidnaps her.